1. Field of the Invention
The present invention relates to a device for detecting a malfunction of a lighting system. More particularly, the present invention relates to a photosensor cover placed over a photosensor of a malfunctioning lighting system to determine whether the source of malfunction of the lighting system lies in the illuminator or in the photosensor of the lighting system.
2. Background of the Invention
A photosensor is an electronic control unit that automatically adjusts the output level of an illuminator(s), e.g., an electric light source, based on the amount of ultraviolet, infrared, or visible light (hereinafter collectively referred to as “light”) detected by the photosensor. In general, photosensors comprise a light sensitive photocell that detects the light; input optics; electronic circuitry that converts the photocell signal to an output control signal; and a housing body for holding the photosensor's components.
Photosensors may operate either by an open-loop system or a closed-loop system. In an open-loop system, the amount of light emitted from an illuminator is determined from a daylight signal, e.g., from sunlight, received by the photocell. Once the daylight reaches a predetermined level, i.e., the threshold amount of light, the photosensor signals the illuminator to turn off. Where the lighting system further comprises a dimming component, a signal proportional to the outside daylight instructs the dimming component to dim the illuminator by an amount proportional to the amount of available daylight sensed by the photosensor.
In a closed-loop system, negative feedback is used to respond to both changing amounts of, for example, sunlight and electric light detected by the photocell. In the negative feedback system, an increase in an input signal level causes a decrease in the output signal; conversely, a decrease in input signal causes an increase in output signal. Accordingly, the more light that is detected by the photosensor, the less luminescence will be emitted by the illuminator; conversely, the less light that is detected by the photosensor, the more luminescence will be emitted by the illuminator.
Oftentimes, when a lighting system comprising a photosensor malfunctions, it is difficult to know whether the source of the malfunction lies in the illuminator or in the photosensor. In order to determine the source of the malfunction during daylight hours, the photosensor must be guarded from the light. That is, if light is blocked from reaching the photosensor, and the illuminator turns on, then the photosensor likely is working and the problem likely lies with the illuminator. Conversely, if light is blocked from reaching the photosensor, and the illuminator does not turn on, then the defect likely lies with the illuminator and/or the photosensor.
Currently, to determine the source of the lighting system's malfunction, practitioners place a dark adhesive tape or a hand glove or mitten over the photosensor to block the light from reaching the photocell. However, such materials have proven problematic. That is, it takes a considerable amount of time to apply and remove the adhesive tape to the photosensor. Additionally such application and removal runs the risk of damaging the photosensor, and the tape is not capable of withstanding the various climatic conditions to which the photosensor may be exposed. Furthermore, it is oftentimes difficult to judge how much tape is necessary to effectively guard the photocell from exposure to the threshold amount of light. With regards to the hand apparel, such materials are unsatisfactory in that they do not adequately conform to the shape of the photosensor, thereby making them inefficient in blocking out the light. Additionally, light is able to reach the photocell by passing through the material of the glove, as well as, up/down and through the opening of the glove. Also, the hand apparel of the prior art is not sufficiently weather resistant to sustain its integrity in the various climatic conditions to which the photosensor may be exposed. Also, a single glove cannot be used to cover a variety of sizes and configurations of photosensors. Accordingly, the prior art has proven inefficient and ineffective in adequately blocking the photocell from exposure to light; thereby, making the determination of the source of the lighting system's malfunction difficult.
Therefore, what is needed is a device capable of adequately shielding the photosensor from light, wherein such device will conform to a variety of sized and configured photosensors, will withstand a variety of climatic conditions, will be readily available to a practitioner, will be easily applied and removed from the photosensor, and will not harm the photosensor.